Featured Research

"Heat Vent" In Pacific Cloud Cover Could Diminish Greenhouse Warming

Date:

March 6, 2001

Source:

NASA/Goddard Space Flight Center--EOS Project Science Office

Summary:

The tropical Pacific Ocean may be able to open a "vent" in its heat-trapping cirrus cloud cover and release enough energy into space to significantly diminish the projected climate warming caused by a buildup of greenhouse gases in the atmosphere.

Share This

The tropical Pacific Ocean may be able to open a "vent" in its heat-trapping cirrus cloud cover and release enough energy into space to significantly diminish the projected climate warming caused by a buildup of greenhouse gases in the atmosphere.

Related Articles

If confirmed by further research, this newly discovered effect – which is not seen in current climate prediction models – could significantly reduce estimates of future climate warming. Scientists from NASA’s Goddard Space Flight Center in Greenbelt, Md., and the Massachusetts Institute of Technology present their findings in the March 2001 issue of the Bulletin of the American Meteorological Society.

"High clouds over the western tropical Pacific Ocean seem to systematically decrease when sea surface temperatures are higher," says Arthur Y. Hou of Goddard’s Data Assimilation Office. Hou and co-authors Ming-Dah Chou of Goddard’s Climate and Radiation Branch and Richard S. Lindzen of MIT analyzed satellite observations over the vast ocean region, which stretches from Australia and Japan nearly to the Hawaiian Islands.

The researchers compare this inverse relationship to the eye’s iris, which opens and closes to counter changes in light intensity. The "adaptive infrared iris" of cirrus clouds opens and closes to permit the release of infrared energy, thus resisting warmer tropical sea surface temperatures, which occur naturally and are predicted to increase as the result of climate warming.

The study compares detailed daily observations of cloud cover from Japan’s GMS-5 Geostationary Meteorological Satellite with sea surface temperature data from the U. S. National Weather Service’s National Centers for Environmental Prediction over a 20-month period (January 1998 to August 1999). The researchers found that cumulus cloud towers produced less cirrus clouds when they moved over warmer ocean regions. For each degree Celsius rise in ocean surface temperature, the ratio of cirrus cloud area to cumulus cloud area over the ocean dropped 17-27 percent. The observed range of surface temperatures beneath the clouds varied by 6.3 degrees Fahrenheit (3.5 degees C).

The authors propose that higher ocean surface temperatures directly cause the decline in cirrus clouds by changing the dynamics of cloud formation and rainfall. Cirrus clouds – high-altitude clouds of ice crystals – typically form as a byproduct of the life cycle of cumulus towers created by rising updrafts of heated, moist air. As these cumulus convective clouds grow taller, cloud water droplets collide and combine into raindrops and fall out of the cloud or continue to rise until they freeze into ice crystals and form cirrus clouds.

"With warmer sea surface temperatures beneath the cloud, the coalescence process that produces precipitation becomes more efficient," explains Lindzen. "More of the cloud droplets form raindrops and fewer are left in the cloud to form ice crystals. As a result, the area of cirrus cloud is reduced."

Clouds play a critical and complicated role in regulating the temperature of the Earth. Thick, bright, watery clouds like cumulus shield the atmosphere from incoming solar radiation by reflecting much of it back into space. Thin, icy cirrus clouds are poor sunshields but very efficient insulators that trap energy rising from the Earth’s warmed surface. A decrease in cirrus cloud area would have a cooling effect by allowing more heat energy, or infrared radiation, to leave the planet.

If this "iris effect" is found to be a general process active in tropical oceans around the world, the Earth may be much less sensitive to the warming effects of such influences as rising greenhouse gas concentrations in the atmosphere. The researchers estimate that this effect could cut by two-thirds the projected increase in global temperatures initiated by a doubling of carbon dioxide in the atmosphere.

The American Meteorological Society is the nation’s leading professional society for scientists in the atmospheric, oceanic, and related sciences.

More From ScienceDaily

More Earth & Climate News

Featured Research

Mar. 3, 2015  Researchers have developed a new way of rapidly screening yeasts that could help produce more sustainable biofuels. The new technique could also be a boon in the search for new ways of deriving ... full story

Mar. 3, 2015  For almost a century, scientists have been puzzled by a process that is crucial to much of the life in Earth's oceans: Why does calcium carbonate, the tough material of seashells and corals, ... full story

Mar. 3, 2015  Major cities in the UK are falling behind their international counterparts in terms of their use of smart technologies, according to a new study. The research has found that smart cities in the UK, ... full story

Mar. 3, 2015  To simulate chimp behavior, scientists created a computer model based on equations normally used to describe the movement of atoms and molecules in a confined space. An interdisciplinary research ... full story

Mar. 3, 2015  Rather than just waiting patiently for any pollinator that comes their way to start the next generation of seeds, some plants appear to recognize the best suitors and 'turn on' to increase the chance ... full story

Mar. 3, 2015  Methane emissions are strongly reduced in lakes with anoxic bottom waters. But – contrary to what has previously been assumed – methane removal is not always due to archaea or anaerobic bacteria. ... full story

Mar. 2, 2015  Hungry, plant-eating insects may limit the ability of forests to take up elevated levels of carbon dioxide in the atmosphere, reducing their capacity to slow human-driven climate change, a new study ... full story

Mar. 2, 2015  Scientists are reporting advances on how to one day make solar cells stronger, lighter, more flexible and less expensive when compared with the current silicon or germanium technology on the ... full story

Solar Plane Passes New Test Ahead of World Tour

AFP (Mar. 2, 2015)  A solar-powered plane made a third successful test flight in the United Arab Emirates on Monday ahead of a planned round-the-world tour to promote alternative energy. Duration: 01:05
Video provided by AFP

Aug. 3, 2011  Carbon dioxide remains the undisputed king of recent climate change, but other greenhouse gases measurably contribute to the problem. A new study shows that cutting emissions of those other gases ... full story

Dec. 9, 2010  Changes in clouds will amplify the warming of the planet due to human activities, according to a breakthrough study that shows that warming due to increases in greenhouse gases will cause clouds to ... full story

Nov. 22, 2010  Global climate models disagree widely in the magnitude of the warming we can expect with increasing carbon dioxide. This is mainly because the models represent clouds differently. A new modeling ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.